Optimization of electroluminescence from n-ZnO/AlN/p-GaN light-emitting diodes by tailoring Ag localized surface plasmon

The localized surface plasmon (LSP)-enhanced n-ZnO/AlN/p-GaN light-emitting diodes (LEDs) were fabricated by inserting Ag nanoparticles (NPs) into the ZnO/AlN interface. To investigate the effects of morphology of Ag NPs on the electroluminescence (EL) of device, the Ag NPs with various sizes were prepared by annealing Ag thin films with different deposition times. It is found that the insertion of Ag NPs with suitable size and surface coverage is favorable for the effective resonant coupling between excitons in ZnO and LSP of Ag NPs, and thereby significantly improve the EL performance of the device. For the n-ZnO/AlN/p-GaN LED with 10 nm Ag NPs, a maximum EL enhancement factor of 3.7 was observed at 420 nm at an injection current of 10 mA. For the device with the smaller Ag NPs, only the weaker enhancement is observed due to the smaller scattering cross section. On the other hand, in the case of the larger Ag NPs, the energy mismatch between the LSP of Ag NPs and the near band-edge emission of ZnO, as well as the poor crystalline quality of the ZnO film, leads to degradation in device performance. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736261]